Moulding machines are known that are arranged for forming plastics to obtain preforms. Such machines can be compression-moulding machines, or injection-moulding machines.
Blowing machines are further known that are supplied with preforms and blow the preforms to obtain containers.
Filling machines are also known that fill containers with a product.
An apparatus is further known comprising a moulding machine for compression-moulding plastics to obtain preforms, a thermal conditioning station for the preforms, arranged downstream of the moulding machine, and a blowing machine arranged downstream of the thermal conditioning station and suitable for blowing the preforms so as to obtain containers therefrom.
The preforms are first compression-moulded, and subsequently removed from the moulding machine to be transferred to the thermal conditioning station, where they are heated to a temperature that is suitable for the blow-moulding step. During the advancing from the moulding machine to the thermal conditioning station, the preforms are arranged sequentially one after the other and move along a preset advance path.
The preforms, after being compression-moulded and before they advance to the thermal conditioning station, require a cooling step that is suitable for stabilising the shape thereof and for avoiding crystallisation phenomena that compromise the transparency of a bottle that is subsequently obtained from the preform and alter the mechanical features thereof.
The duration of the cooling step depends on the type and/or on the geometry of the preforms. Thus, a given period of time required for the cooling step corresponds to a given geometry and/or type of preform. For given types or geometries of preforms it is necessary to slow the moulding machine so as to support the preforms for longer, thus enabling suitable cooling. This entails an undesired reduction in productivity in all those cases in which it is not possible to modify cooling efficacy.
The preforms, before being positioned on the blowing machine, have to be suitably heated, and for this purpose remain in the thermal conditioning station for a further set period of time that is a function of the geometry and/or of the type of preforms thereof.
A drawback of the aforesaid apparatus is that it has productivity that is limited by the time required for the preforms to be thermally conditioned. In particular, the productivity depends on the period of time that the preforms, arranged in sequence one after another along the advance path, require for the cooling step that is subsequent to compression-moulding.
In other words, the operation of the moulding machine located upstream and of the blowing machine located downstream depends on, and is constrained by, the period of time required for cooling the preforms that have just been moulded, this period of time depending on the type/geometry of the preform.